Thickener

Abstract

A thickener for liquids or pulps comprising a tank in which flocculation takes place and dilute liquid is displaced toward the top of the tank, a feedwell having a bottom opening in fluid communication with said tank, conduit means to supply feed liquid to said feedwell, and apertures in said feedwell or said conduit disposed above said bottom opening and positioned to permit the flow of said dilute liquid directly from the tank into the feed liquid for dilution thereof. The thickener preferably comprises a weir plate assembly connected with a side wall of the feedwell adjacent a side opening therein. The weir plate is preferably moveable by means of a float assembly between an open position permitting said dilute liquid to flow from the tank to the feedwell, and a closed position substantially closing the side opening.

I claim: 
     
       1. A thickener for liquids or pulps comprising a tank in which flocculation takes place and dilute liquid is displaced toward the top of the tank, a feedwell having a bottom opening in fluid communication with the tank, a conduit for supplying a feed liquid to the feedwell, an aperture formed in the feedwell above the bottom opening and positioned for the flow of the dilute liquid directly from the tank into the feedwell for dilution of the feed liquid therein, and a weir plate mounted on the feedwell for movement between an open position for flow of dilute liquid from the tank into the feedwell and a closed position substantially closing the aperture. 
     
     
       2. A thickener according to claim 1 wherein the aperture comprises an opening in a side of the feedwell. 
     
     
       3. A thickener according to claim 2 wherein the weir plate has an upper edge that forms an effective lower edge of the aperture. 
     
     
       4. A thickener according to claim 3 wherein the weir plate is pivotally connected to the feedwell below the aperture and includes side panels in slidable sealing engagement with the feedwell. 
     
     
       5. A thickener according to claim 1 comprising weir plate adjusting means for adjusting the position of the weir plate means in response to variation in liquid level in the feedwell. 
     
     
       6. A method of thickening liquids or pulp in a tank in which flocculation takes place and dilute liquid is displaced toward the top of the tank comprising supplying a feed liquid via a conduit into a feedwall having a bottom opening in fluid communication with the tank and an aperture below an upper edge of the feedwell, and opening and closing the aperture by a weir plate mounted on the feedwell in accordance with the level of liquid in the feedwell to direct a selected flow of said dilute liquid through said aperture.